The present invention relates to a decoding apparatus and a decode processing method.
In a third-generation mobile radio communication system, rate matching processing is often carried out in coding or decoding received/transmitted data. The rate matching processing is processing in which a transmitter side increases or decreases the number of bits of data to adjust coded data to a frame length and a receiver side decreases the number of bits corresponding to the number of bits increased by the transmitter side, or increases the number of bits corresponding to the number of bits decreased by the transmitter side. In the explanation set forth below, processing for increasing the number of bits of data performed by the transmitter side refers to as xe2x80x9crepetitionxe2x80x9d while processing for decreasing the number of bits of data performed by the receiver side refers to as xe2x80x9cpuncturingxe2x80x9d with respect to repetition performed by the transmitter side.
The following will explain the state in which data subjected to repetition by the transmitter side is subjected to puncturing by the receiver side with reference to FIG. 1. FIG. 1 is a view illustrating a conventional puncturing method performed by the receiver side.
It is assumed that data sequence subjected to error correction coding is data sequence of 8 bits {d1, d2, d3, d4, d5, d6, d7, d8} in the transmitter side in the upper portion of FIG. 1. It is also assumed that the number of bits per one frame is 12 bits.
The transmitter side performs repetition such that an increase in energy in the frame after rate matching becomes even in accordance with a given algorithm. Accordingly, d1, d3, d5, and d7 are repeated respectively and a data sequence after the repetition results in {d1, d1, d2, d3, d3, d4, d5, d5, d6, d7, d7, d8} as illustrated in the upper portion of FIG. 1. From data sequence after the repetition, it is shown that arbitrary three continuous bits include two increased bits and one non-increased bit, resulting in the equal distribution of an energy increase in the data sequence.
On the other hand, the receiver side performs puncturing to data subjected to repetition by the transmitter side as illustrated in the lower portion of FIG. 1. Namely, if the data sequence demodulated by the receiver side includes {d1, d1, d2, d3, d3, d4, d5, d5, d6, d7, d7, d8} as illustrated in the lower portion of FIG. 1, the data sequence after puncturing results in {d1, d2, d3, d4, d5, d6, d7, d8}.
However, in the conventional puncturing method performed by the receiver side, as is obvious from the lower portion of FIG. 1, data subjected to repetition by the transmitter side (d1, d3, d5, and d7 in the example illustrated in FIG. 1) is discarded to perform puncturing.
It is an object of the present invention is to provide a decoding apparatus and a decode processing method capable of enhancing the effect of error correction decoding through the effective use of data, which is conventionally discarded, at the time of puncturing performed by a receiver side.
In order to attain the above object, according to the present invention, data subjected to repetition by a transmitter side is added without being discarded to increase likelihood of data at the time of puncturing performed by a receiver side, making it possible to enhance the effect of error correction decoding.